1. Field of the Invention
The present invention relates to spindle devices for spinning machines and, more particularly, to a spindle device for a spinning machine of the pneumatic type, in which a twisting force is applied to roves with a spinning stream of compressed air and thereafter the roves are passed through a rotating thin tube to be spun.
2. Description of the Prior Art
A spindle device as shown in FIG. 4 has hitherto been known as the above-mentioned type of spindle device. This spindle device is so arranged that a small-diameter tubular spindle 1 is rotatably installed in a housing 2 via a pair of rolling bearings 3, and a cap 5 having a plurality of nozzles 4 for spouting jet air is provided at a tip portion of the tubular spindle 1. The tubular spindle 1 is driven to rotate by a motor comprised of a rotor 6 secured to the tubular spindle 1 and a stator 7 secured to the housing 2. The nozzles 4, provided in a peripheral wall 5a of the cap 5 as shown in FIG. 2, makes a spinning stream within the cap with jet air spouted from the nozzles 4. Then, this spinning stream of jet air gives a twisting force to roves 9 introduced into the cap 5 through an inlet 8, the roves 9 being then further twisted and passed within the tubular spindle 1 rotated by the motor to be spun. A thread 9' thus fabricated is wound up around a roll, which is not shown.
As another available method for driving the tubular spindle 1, the motor comprised of the stator 7 and the rotor 6 may be substituted by an arrangement in which an external motor and the tubular spindle 1 are connected to each other with a belt.
However, in the above-described prior-art spindle device for use in a spinning machine, one problem is that there is a need for providing a rotational drive mechanism for the tubular spindle 1, resulting in a large size device as a whole, while the motor act as noise source, causing great noise. Another problem is that the rolling bearings 3 supporting the tubular spindle 1 cause metal-to-metal rolling friction such that the bearings 3 are susceptible to damage, resulting in a shorter life. Yet another problem is that waste threads floating around the tubular spindle 1 can invade inside the rolling bearings 3.